Artificial gills for deep diving without incurring the bends and for scavenging O2 from and dispelling CO2 into water or thin air

An artificial gill for deriving and concentrating O2 from seawater and discharging CO2 to the seawater comprising:

• (a) a plurality of serially joined modules, each comprising a housing containing a plurality of tubular fibers of a semi-permeable membranous material arranged as a bundle to create an effective O2 and CO2 exchange contact area, each housing of each module having first and second inlet ports and first and second outlet ports configured so that fluid passing from the first inlet port to the first outlet port bathes exterior walls of the tubular fibers and fluid passing from the second inlet port to the second outlet port passes through lumens of the tubular fibers;
• (b) means for coupling the second inlet port of a first endmost module to a diver's blood source and the second outlet port of the first endmost module to the diver's blood return;
• (c) means for flowing seawater only through the second endmost module of the plurality of serially joined modules from the first inlet port of the second endmost module to the first outlet port of the second endmost module;
• and
• (d) means including a pump for each of said modules for circulating hemoglobin rich liquids from the second outlet port of any of the plurality of modules to the first inlet port of an adjacent module and from the first outlet port of said adjacent module back to the second inlet port of a next preceding module and where the exchange contact area and contained volume of each of the adjacent serially joined modules decreases in progressing from the second endmost module to the first endmost module whereby the concentration of O2 increases in progressing from the second endmost module to the first endmost module.